In a leak detector, the ducts connecting the various components do not all have the same diameters.
In particular, the duct(s) connecting the enclosure to be tested to the secondary pumping set is/are larger in diameter than, for example, the duct connecting the primary pumping set to the secondary pumping set. In an automatic detector, it follows that the valves situated on the different ducts do not all have the same pass diameters.
Although for low-conductance ducts having inside diameters of less than 10 mm, electromagnetic valves are relatively cheap and compact, on high-conductance ducts having inside diameters for example in the range 16 mm to 40 mm depending on the circumstances, electromagnetic valves are bulky and expensive.
However, in portable detectors, electromagnetic valves are used on all the ducts. In contrast, pneumatic valves are used for the large valves of console-mounted detectors, which pneumatic valves are actuated by an air compressor or by an air suction source included in the detector itself.
However, such a solution may hardly be applied to portable detectors because of the resulting increase in volume and in weight, as well as the increase in cost and in energy consumption.
An object of the invention is, therefore, to provide a solution to this problem and the invention applies particularly, but not necessarily, to portable detectors.